A method of perfusing the pregnant sheep uterus has been developed and evaluated. The method effectively controls collateral circulation and produces estimates of uterine blood flow and oxygen uptake comparable with published studies. In the pregnant uterus, perfused at constant flow, stimulation of the distal end of the right sympathetic chain (1 ma current for 1 msec) at frequencies between 5-25 cps produced a graded increase in perfusion pressures. Maximum stimulation produced an average 30% increase in perfusion pressure. The response was blocked by dibenzylene.